The present invention relates to a rolling element clutch. A rolling element clutch is known, which has an outer ring, an inner ring and one row of rolling elements mounted on either side between the outer and inner ring. A plurality of clutch rollers are mounted between these two rows in the space between the two rings, these rollers giving way for free-wheeling during relative rotation of the two rings in one direction and stop relative rotation when relative running occurs in the opposite direction (German Edition xe2x80x9cMaschinenelemente,xe2x80x9d G. Niemann, H. Winter, Vol. III, second completely revised Edition, Publishing Company Springer (1986), page 278, FIGS. 30/27b).
An important disadvantage is to be seen in the fact, that the clutch rollers of this known clutch may become jammed and abruptly blocked during their engagement between the two rings. The machine elements which are connected with the clutch members may then produce rather high inertia forces and corresponding high jamming forces within the clutch, these forces overloading the torque transmitting contact surfaces in the clutch. Moreover, the clutch rollers are difficult to become manufactured since they have a very complicated shape. The clutch rollers are also difficult to get mounted into the clutch, which results into a laborious assembly procedure and an expensive manufacture of the known rolling element clutch.
One object of this invention is to establish a rolling element clutch, where the machine elements connected with the clutch become relatively smoothly braked and blocked during rotation of the inner ring in blocking direction.
A further object of the present invention is to provide structural clutch members, which have a simple shape and which can be manufactured easily by using economical mass production methods.
In the rolling element clutch of this invention there is mounted a ring-type cage between an outer ring and an inner ring. This cage has a plurality of circumferentially spaced recesses, i.e. cage pockets. In each pocket is incorporated a controlling insert. At least one clutch roller is mounted on either side of each controlling insert. Every clutch roller has an outside end, which penetrates into an outside cavity in an axially inwardly showing side wall of the corresponding pocket, and an inside end, which penetrates into an inside cavity in an axially outwardly showing side wall of the controlling insert. Every controlling insert of the cage is carried by rolling elements, which freely roll in one or the other circumferential direction between an outer race of the outer ring and an inner race of the inner ring.
In the rolling element clutch of this invention each controlling insert of the cage ring becomes displaced within its pocket of the ring cage by the driving rolling elements, the direction of displacement depending on the rotational direction of the inner ring in freewheeling direction or in blocking direction. Thereby, each insert is guided sliding on adjacent wall portions of its cage pocket.
In case the inner ring rotates in freewheeling direction, then each control insert is driven by the rolling element and displaced circumferentially in its pocket. During this displacement the controlling insert slides on adjacent sidewall portions of the pocket and on the bore surface of the outer ring and/or on the outer surface of the inner ring. The clutch roller on either side of each controlling insert is being gripped between the outside cavity in the side wall of the cage ring and the corresponding inner cavity in the axially outwardly showing sidewall of the controlling insert and becomes finally axial adjusted.
The magnitude of the displacement distance of each controlling insert is preferably limited by an adjacent terminating edge wall in the pocket, which locks the displacement movement of the controlling insert, thereby ensuring alignment position of both clutch rollers at the end of displacement of the controlling insert. The inner ring is then able to rotate in freewheeling direction within the rolling element clutch.
In case the inner ring starts to rotate blocking direction, the cage ring may still somewhat rotate in freewheeling direction or may have come to a standstill. Each controlling insert of the cage ring is then driven by their rolling elements in blocking direction and displaced in its cage pocket accordingly.
The inside cavity of the controlling insert gets displaced relatively to the outside cavity of the cage pocket, whereby both opposite cavities of the clutch roller grasp the corresponding ends of the clutch roller and turn the clutch roller so that it starts to become inclined with respect to radial planes.
The inner ring continues to rotate in blocking direction and the clutch rollers become more and more inclined. Finally both ends of each clutch roller are becoming jammed between the corresponding inner raceway of the inner ring and the outer raceway of the outer ring, so that further rotation of the inner ring relative to the outer ring is blocked.
During the inclining movement of the two clutch rollers of each controlling insert and final blocking of the inner ring there may be produced axial forces in the contacts of both clutch rollers between inner raceway and outer raceway which push each clutch roller into the inside cavity of the axially outwardly showing sidewall of the controlling insert.
Since the axial forces of both clutch rollers of every insert act oppositely to each other on the controlling insert, the resulting axial force on the controlling insert is relatively small. The rolling elements, which support each controlling insert between inner ring and outer ring, carry relatively small axial reaction forces accordingly.
Braking during rotation of the inner ring in blocking direction occurs relatively slow, because of gradually growing sliding and jamming resistance of the clutch rollers during the clutch roller""s inclining movement.
In case the inner ring begins to rotate in freewheeling direction then each controlling insert of the cage is driven by its rolling elements in freewheeling direction and the blocking contacts of the clutch rollers between outer raceway and inner raceway are becoming loosened. Accordingly.
Each controlling insert gets displaced within its cage pocket coming finally to a rest against an edge wall of the cage pocket. Concomitantly, all clutch rollers of the cage ring are getting aligned axially, so that they are able to freely roll in freewheeling direction between the corresponding inner and outer raceway again.
In the space between inner ring and outer ring there may be filled in a lubricant, which lubricates the active contact surfaces of the clutch rollers and of the rolling elements, thus protecting them from detrimental Sliding and/or rolling contact damages. Such lubricant may be a conventional oil or grease which contains suitable additives.
The rolling element clutch of this invention has a rather simple construction. The clutch can be equipped with conventional rolling elements, which are able to become manufactured in an extremely economical mass production.
The second embodiment of this invention has the effect, that the clutch roller have an extremely simple shape, which is normally used for cylindrical roller bearings.
In a third embodiment the face of the outside end and the face of the inside end of each clutch roller is spherically formed, each face being conform surrounded and narrowly gripped by the adjacent outside cavity or by the adjacent inside cavity respectively. This feature brings the effect, that both ends of each clutch roller are freely articulated in their cavities.
During rotation of the inner ring in blocking direction there are produced braking forces in the contacting surfaces between the inclining clutch rollers and their inner and outer races, some components of these forces may act in one or the other axial direction. They are transmitted via the spherical faces of the clutch rollers to the corresponding cavity of the cage ring or of the controlling insert and, thus, taken by the cage or by the controlling insert.
In a forth embodiment, both ends of each clutch roller have a smoothly reduced outer diameter so that these ends get a closer osculation on their raceways when the rollers become inclined and gradually jammed between the raceway of the inner ring and the raceway of the outer ring. This feature brings the effect, that the contact forces between the clutch roller ends and both raceways during inner ring blocking are taken by large contact surfaces and reduced accordingly. By this way overloading of the contact surfaces of the ends by too high jamming contact forces is avoided.
In a fifth embodiment the clutch rollers become inclined to a relatively great inclination angle until they assume their blocking inclined position between the inner and the outer raceway. This feature brings the advantage, that relatively high torques can be taken by the clutch during blocking.
A sixth embodiment has the effect, that each controlling insert revolving together with the cage ring in the clutch is held axially in the clutch by ball shaped rolling elements, which run in circular grooves between the inner ring and the outer ring.
A complementing seventh embodiment gives the advantage, that the ball shaped rolling elements can be mounted easily between the outer ring halves and the inner ring.
An additional complementing eight embodiment shows the possibility for the ball shaped rolling elements to become easily adjusted between the inner ring groove and the outer ring groove, so that even a certain xe2x80x9cnegative clearancexe2x80x9d can be adjusted between rolling element and raceway, which causes a preload on the rolling elements. The preload avoids sliding movement of the rolling elements on their raceways during driving of the corresponding controlling insert in freewheeling or in blocking direction. The development of detrimental sliding marks on the raceways of the rolling elements is counteracted accordingly.
A ninth embodiment has the effect, that each controlling insert, which is sliding and guided on circumferentially extending sidewalls of its pocket during becoming displaced in freewheeling or in blocking position, has to overcome a certain rotational resistance of the cage ring.
This rotational resistance may be produced by one or more rubbing element rings, which rub on the outer or the inner surface of the cage ring, thus somewhat hindering the cage ring to rotate freely in the clutch. The rubbing element rings are preferably mounted on either end side of the clutch. Such rubbing element ring may even be a common sealing ring, for instance an elastic o-ring, made from a fluorine containing polymer, which causes a rather small rubbing resistance. The o-ring can easily be snapped into a circular groove of the inner or of the outer ring respectively, thereby closing an interior space of the clutch to the outside. A lubricant may be filled into this interior space to lubricate the sliding and rolling surfaces of the clutch elements during operation of the clutch. This lubricant is prevented from escaping from the interior of the rolling element clutch to the environment by the sealing o-rings.
A tenth embodiment has the effect, that the cage ring is held centrically between the inner and the outer ring. The rotating cage ring may be held and slide on a circular portion of the outer surface of the inner ring and/or on a circular portion of the inner surface of the outer ring.